Method of and apparatus for glazing ceramic ware



c. DRESSLER 1,919,322

METHOD OF AND APPARATUS FOR- GLAZING CERAMIC WARE July 25, 1933.

Filed Oct. 3, 1930 4 Sheets-Sheet l UZON OZ E-(UZUkL g E g g g INVENTOR.

CONRAD fi m-5545? w 2 W A TTORNEY n a n u I :I m L nEON H3222. L uzoN hin' HZON @2380 INVENTOR.

, I i ATTORNEY CONRAD 0/?[551 ER 4 Sheets-Sheet 2 July 25, 1933. c. DRESSLER METHOD OF AND APPARATUS FOR GLAZING CERAMIC WARE Filed Oct. 3, 1950 C. DRESSLER July 25, 1933.

METHOD OF AND APPARATUS FOR GLAZING CERAMIC WARE Filed Oct. 3, 1950 4 Sheets-Sheet 3 IN VEN TOR. Cow/m0 Dfizsszar A T TORN E Y Patented Julv 25, 1933 E STATES;

CONRAD DRESSLER, on PARIS, FRANGE, ASSIGNOR TO SWINDELL-DRjESSLERQ CORPORA- TION, OF PITTSBURGH! rnmrsrnvertrxan CORPORATION OF PENNSYLVANIA METHOD OF ANnAPrAnATUs FOR G AZIN cE RAriIowARE i My present invention relates to the constriiction and niode ofoperation of kilns andv kiln apparatus and particularly, of a contina hightemperature, is passed into a chamber atmosphere vvholly or largely consistingot a] glazing agent. such as common saltfin a vaporizedcondition, the clay at the exposed surfaces of the Ware combines with portion oi the salt vaporv present to form silicate of soda. The Vitreous coating, sofforined he comes hard and tough whenthe Ware is; properly COOlC(l-.,"CQ1'UD1C Ware so treated is improved. in appearance, increased in strength and capable of -a prolonged comiiiercial. lite... he use ofc vai'eglazing agent is quite ex'teiisivefor certain heavy clay articles, because oftheexcel lent qualitv of the glaze ohtainedand the relatively low cost of this method of appli cation. ii-Wetofore in use and particularly. when applied to the-glazing ofliollowor tubular Ware, such as ceiainic conduit tile or sevver pine, have been in many cases disadvantage? ously characterized by tlielack ofunil'orm Iit oft ie glaze on the. War-J an excessive Waste of t e glazing asueiit a substantial.

' through'an exhaust portonly;

animint oii' h lane of the were treated.-in adequate control. of operating Conditions. and a low th ermal eflicienc v of the kilnsfused. I

The general. obj of my present invention is the provision oi aniniprovedconstruction and mode of operationot a. continuous tunnel. kiln and apparatus for use therewith. all esnecia in in process. A further object is the provis on oian.ininroved W..re g Zliipf process.

A more suecitic. ohject is the 'nrovision oi a glazing k ln having an improved construe tion and arrangement of the'lriln heating and glazing provisions. Another snocific'oh ]ect is the provision of a tunnel .ilu having means torefiecting: recirculation of the l ilnatmosphere in the glazing: zone. Another struction;f i i i i Y i Fig, 9 is a'transverse vertical-section of object is the provision of a trnck'esneinion salt as the Glazing. processes and. apparatus Fig. 2 "is a vievv adapted forcari'vi 5! out. a salt] I the, line-5..5 of Fig. 2, illustrat ng the kiln truck construction;

construction Application fl ed Qctober 3 1930. Serial, no. 4. 6.152.

porting large size luillow Ware through a giazing 'lilllli; and" r'iecial'ly a lvantageous PAT venif Whei'i used with iinprove'dheating and glazing nrovisionsjiiiiother object. is the provision of an -'open.fire tunnel kiln having its" heating provisions intliefurnace zone constructed and arrangedto"avoidlocal over-' heating of and iinpinge ncnt'of the burning' fuel on tlieivare onthe'ioutsid etofithe trucks .00.

when in openly exposed vhirination"thereon,

'andfto provide amorelun'ifori'n distributionx of the heat supplied to the hollow IW'are" throughoutthe kiln chamber; i I The various features oi" novelty: which characterize my invention are pointed out ith particularity. in the claims annexed to and forming a partof this specification. For a better understanding of the, invention,

however, and the advantages possessed by it, reference should be had to the accompanying drawings and descriptive matter in which I 1m illustratedand described preferred em-:

bodimetsLof the invention.

'1 Of the "drawings Fig. 1 is a somewhat diagrammatic planf7 view of a salt glazingkiln incorporating ny improvements; v illustratingin its left half a vertical, section throughjai saltinghurner chamber and exhaust port in the glazing zone and in; its right half a vertical section Fig. lSfi. longitudinal vertical sectionion the line of Fig. 2 illustrating the gl tz ing zone side Wall construction; a r 1 Fig. 4 is a longitudinal horizontal see tion. onthe line 4,-14 of. Fig. 2' illustrating the glazingzone construction Fig. 5 is a longitudinal, vertical section on Fig. 6 is a transverse vertical section' 1 Figl 8 is a vertical: section on line 8 .8 L

of Fig. 1.; illustrating the cooling zone conion 'trated in Figs. "lto 8, A'designates a con.-

tinuous tunnel kiln having an elongated kiln chamber or ware passageway A and divided longitudinally into a plurality of communicating zones or'secti'ons indicated in Fig. 1

as a preheating zone A extending from the entrance end-of the kiln to a furnace zone A which in turn extends to a glazing or salt zone A cons sts of a cooling zone i be reat-ed is moved through theklln on a The remaining p rtion of the kiln train of kiln cars or trucks B arranged to run on railsB at the bottoniof thekiln cham ber. Thekiln is constructed in the usual manner with verticalside walls A and an arched roof A, having refractory inner wall portions A covered suitable insulating material A". 'The kiln'is constructed on a;

- concrete base A andthe walls reinforced by buckstays and tie rods in a well known temperature conditions in thevarious sect1ons of the kiln chamber and particularly manner.

Successful operation of a tunnel kiln largely depends upon an effective control of in the furnace. zone. In the kiln illustrated the furnacezone A. formsa substantialpon tion, of the kiln length and, as illustrated in; Figs. 1 and 6, is formed with a pluralityi'of oppositely arranged burner chambers C,

which extend horizontally and transversely in each side wall of the kiln and 'co1nmuni-. cats with the kiln chamber A through ports,

, C. The inlet ports C preferably'open to "the kiln chambersli 'htly below the platform level ofthe kiln trucks passing through the chamber. Y v

Each burner'chamber encloses a fluid fuel burnerD connected to an external fuel supply pipe D by branchpipes D and arranged for axial adjustments relative to a refractory block C positioned in the burner chamber at its innerle'nd and formed W th a VenturiDas-Q age C therethrough. The fuel burners i1.

lustrated are primarily intended for use with fuel gas partly premixed with air. The 'imount of air premixed with the gas is preferably less than theamount required f or' complete combustion.

C? located-in the lower portion of the corresponding side wall A; :A connection. therewith to the individual burner chambers is ,1 provided by ports. C controlled by externally operated slidable dampers C The'ports C The ware to" out No. 1,615,217, granted January 25, 1927.

tudinal spacing of the burners.

in Fig. 1, the fuel burners are gradually zone. visions similarly regulated, a progressively lncreasing temperature will be lmaintained The additional air re, quired V for combustion is preferably pre-- heated and supplied to the burner chambers "'hrough' 'a longitudinally extending air duct are advantageousl 1 located ad'acent the outer end of the Venturi blocks C to subject the orts to the asniratin action of the aseous mixture passing through the Venturi passage C When any damper C is open, air is drawn through the corresponding port C and discharged with the premixed air and gas into the kiln chamber. The aspirating effect of the burners can be regulated by axial adjustment of the burner relative to the Venturi passage and'the parts are so proportioned and arranged that the-aspirating effect can be regulated to produce either a reducing'or oxidizing atmosphere in the adjacent portion of thekilnchamber. Individual control of the fuel supply to each burner is advantageously obtained by regulating provisions such as illustrated in Dressler Pat- The combination-of regulation of the fuel supply to the individual burners and the regulation of the character of the combustion at each burner enables the operator to readily obtain the most desirable operating conditions in different portions of the furnace zone. The dampers C are generally posi tioned only in afully open or fully closed position as to attempt air regulation by their adjustment is relatively impractical. The outer end of-each burner chamber is normally closed by a removable block C to prevent the entry of Junpreheated atmospheric air. The substantial length of, and large number of fuel burners in, the furnace zone will be noted, and also the particular longi- As shown spaced closer together as they approach the glazingzone A. 'These factors greatly contribute to the accurate control of temperature conditions and the maintenance of a gradually rising heating curve in thefurnace With the above construction and arrange ment, combustible gas nnxtures are discharged into oppositesides of thefkiln-cham ber at a large number of points in the furnace With the fuel supply controlv proalong the length of the furnace zone.

The preheating zone A arranged between the furnace zoneand the entrance endof the kiln is of slightly greater length than the 1 furn ace zone. A closeregulation of the temperatnre conditions in the preheating zone is obtained by a series of longitudinally spaced exhaust ports E at'the kiln bench level 'in-the' slightly enlargedportion thereof indicated in Fig. land. which open to a longitudinal duct E leading to a stack connection E The heating gases generated in the furnace zone are thus drawnlongitudinally through the preheating zone in contact with the ware therein and the amount of gas withdrawn mam 1 portant when" the ware contains carbon or sulphur constituents. j The present arrangement of thepreheating' zone with a su'bstan tial length and with the exhaust regulating provisions described permits the 1nainis tenance of the desired. temperature reg'ula tion'anddistribution of the heating gases to the ware in that section of the kiln. V f

The trucks B for carrying the war-e through the kiln are of a special design particularly adaptedfor use in a tunnel kiln of the type described herein. As illustrated in 'Figs. 2, 4;, 5 and 6, the lower portion of each truck is'cons'tructed in a well known, manner with; running gear B a cast steel frame B and 2.5. a refractory base B". The truck superstructure consists of a series of horizontal refrac' I tory slabs B on which are mounted a double series of closely spaced refractory. girders v B, the girders of each series exten ding transversely across half the truck width. The upper surfaces B of the girders are fiat to pro' vide a ware supporting platform and the girder sides are'suitably shaped to forma' plurality of transverse channelsB 'separated by the vertical sections of the girdersl The channels B openalong their length to the' chamber space above the truck platform through restrictedslots B asshown in 4 and 5. The truck. channels open at the f sides of the kiln chamber at the level of the inlet ports C' of the burner chambers and by which arrangement, the combustible gases discharged through the ports will pass directly-into the truck channels. The

platform is of substantial area and permits.

' the transportation of ware pieces of different sizes without interferencewith the circula tion of gases through the slots B. Free expansion and contraction of the slabs1B5and girders B are permitted by the expansion jonts B shown between ad iacentiparts. @By the abovc arrangement all of theware is positioned above the level of the burnerports vC and outof the direct horizontal path-of.- the burning gases. illustrated is particularly advantageous for The truck construction 1 carrying hollow ware and will provide a uni form distribution of the heating gases to the f ware pieces in all parts of'the truck.

The kiln section forming the glazing zone Af'is, as shown in Fig. 1, of slightly greater cross-sectional area than the other p'ortions'of the kiln. The height of the 'kiln chamber is 5 increased to provide a combustion space J I of-substantial Volume above the' top. of the ware. This combustion space is limited 1on gitu'dinally byia pair of vertical bafiiesl J 1 dependingfrom.-the arched roof of thekiln' and extending across substantially allof the; chamber" area above theware .:The roof is formed with. a pyrometenopening 1J as shown The glazing zonekiln sectionis constructed with aseries of transversely extending-1011-; g'itudinally spaced burner chambers .F' ar.

ranged in opposite side walls .of the kiln and preferably opening tothe kilnchamber through inlet ports .Fat a level above'the top of the ware on. the trucks. A salting burner F connected bypipe F and F to an external supply of premixed air and gas is axially arranged in eachburner chamber. F

. insubstantiallythe sa-memanne'r as'the furnace zone burners and axiallyiadjustable relative to a Venturi blockF at the'burner chainher inner end. The outer end :ofeachchamher is normally closed bya removable block The ware glazing agent, preferablycom 'mon salt, to be delivered in a vaporized con-1 dition to the'ware in the kiln chamber, is

stored in an external hopper G adj acent. each burner and adapted to be withdrawn there from by a rotating screwconvey'or G. "This screw discharges into a-vertical'pipeG opening at its lower end into the supply-pipe Fi. The-velocity of the premixed air and gas passing through the pipe F from the source of supply issuflicient to. entrain the salt dropping through "the pipe G and carry it in a finely divided conditionfthrough the Venturi I I blockF? and port, F into the kiln chamher-section J, where it'is vaporized by the heat 1 generated byathejiburning fuel.

The intimately .mixed salt fumesqand highly heated products offlcoinbustion are passed downwardly around and through thexware and into the truckchannels B The side walls inthis' portion of the 'kiln are provided atthe'kiln bench level with a plurality of horizontally and transversely arranged exhaust; passages H closely spaced longitudinally and connccted adjacent their outer ends to exhaust or fume collecting ducts H through ports H controlled externally operated slidable dampersfH The number of exhaust pasthe passages .11 are closed by. removable blocks H The exhaust ducts H extend'lo n-- gitudinally throughout the glazing zone and are connected at oneend to an induced draft connectionI-P.

In the operation of glazing apparatus of 115,. f sages ,isgsubstantially greater than the 1 number ofsalting burners. The outer ends of the 3character descibed,y a large proportion] j.

of the salt fumes passing through the charm. ber isnot absorbed by thewaren This 'has heretofore been wasted in kilns. of the char- I f acter described. T0 substantially reducethis waste. of, material and consequently the ,cost I off-glazing, I have; provided a recirculation I desired. I

system for returning'a-portion ofthe unabsorbed salt fumesto the kiln chamber in the glazing zone. In-the present construction vertical recirculation fiues :K are formed in the kiln side walls'connecting certain of the exhaust passages H. to corresponding salt; ing burner chambers F. -The lower end of each vertical fine is controlled by a slidable damper K, and the upper end, openingto the burner chamber, by asimilar damper' K With this construction and the corresponding dampers H closed and dampers K- and K open the aspiratingefl'ect of the gases passing through the Venturi block F is sufficient to create a strong suction in the fines K causing salt fumes and products of ing atmosphere in the kiln chamber, means are. provided for effecting a neutral or an oxidizing atmosphere.- As illustrated in Figs, '2 and 3', the preheated air duct C is connected to each of the vertical flues K by a short vertical passage K ficontrolled by a slidable damper K which,-when open, permits a supply of air to be drawn up the flues K by the aspirating action of the burners.

3 The dampers K, K? and K can be easily adjusted to regulate the amount of preheated 'air for combustion and recirculated salt fumes passing through the flues: K-to the salting burners iii-whatever proportions are r The wareafter being fired and glazed is passed through the cooling zone A adjacent th exit end ofthe *ki'ln. It is highly important in tunnel kiln practice, and particulary Where a glazing process is'being carried out, to'so regulate the cooling action as to avoid the cracking of the ware and rupture of the kiln structure which tends to occur a when the temperature conditions in the cool- 'ng zone'vary from the normal curve. This portion of the kiln is constructed with. side wall and roof passages N and N ,.res pectively, as shownin Fig. 8, to permit the flow therethrough of a cooling medium. The tooling medium is preferably atmospheric air admitted at longitudinally spaced -controllable inlets N in the side walls. The air thus admitted absorbs heat radiated to the kiln structure'by the'ware and is subsequent '69 l y drawn from the cooling space N by a hot air fanN through a conduit N connected thereto at one or more points N along its length,'as indicated in Fig. 1.' The heated air'exhausted by the fan is delivered to the kiln chamber through a special nozzle N at the under side of the kiln crown adjacent the exit end of the kiln.- The heated air passes into" direct contact with the ware on the trucks and is drawn longitudinally I through the cooling zone to air outlets N adjacent the exit end of the glazing-zone. The heated air passes from the outlets N into the air duct C in the side Wallsv and is utilized as previously described. 7

Vhenever the amount of'air exhausted by the fan N exceeds the, amount required for direct cooling of the ware and combustion, the excess may be utilized inseparate ware driers or for plant heating. The kiln structure at the rearmost portion of the cooling zone is formed by a steel walled casing N of reduced'size, which construction provides a more rapid indirect cooling of the ware before the trucks emerge from the kiln.

Uninterrupted service of kilns used. for

salt glazing has been extremely difficult heretofore because of the extensive deposits of the glazing agent on the exposed portions of the kiln structure, which cause rapid: de-

terioration of the kiln structure and clogging of the fume passages. The present kiln section in the glazing zone is so constructed as to permit periodic cleaning of the various passages without interrupting the operatlon of the kiln. Clean-out openings K are formed in the upper side walls of the kiln directly above the vertical flues K. Suitable tools can be inserted throughthe: openings when the dampe'rsK and K are opento remove salt deposits-from the fiues'K; The exhaust passages H can be rendered accessible for cleaning by removingthe'blocks. H The Ventur'i passage and inlet port F are rendered accessible when the correspondlng burner is temporarily shut off, by removing the blocks F. These portions of the kilnstructure are continuously exposed to clogging and deterioration and the above provisions substantially eliminate any trouble of this character.

With the kiln structure and apparatus 0on structed and arranged as described, trucks loaded with the ceramic ware to be treated are periodically introduced into the entrance end of'the kiln. The trucks are shown loaded with a large number of pieces of conduit tile W stacked in a double tier on the truck plat forms, although it will be understood that other kinds of ware and stacking arrangements than that shown can be readily used.

The trucks are slowly advanced through the kiln chamber by the periodic operation of a truck pushing mechanism of a well known character. The ware during its passage through the preheating zone is gradually and uniformly heated to a predetermined temperature before entering the furnace The "p rogressively closer spacing of the burners in the furnace zone and the permissible individual regulation of each burner 1 zone.

dizing byadjustingthe recirculation flueconjenables the operator to regulate the temper-, ature conditions therein to bring the ware to its-maximum temperature before passing into the glazing zone.

The combustible mixture discharged from each burner chamber C passes through the ditions throughout the length of the com-i bustion channels from which the burning gases move upwardlythrough the multiplicity of channels formed within and between the individual ware pieces. The burner ar rangement and truck construction insures a uniform distribution of the heating gases throughout all portions of the Ware. The heating gases passing upwardly in intimate contact with the ware are drawn longitudinally through the kiln towards the entrance end thereof and into and through the preheating zone by the'draft creating means provided. Any tendency towards longi-' tudinal movement of the kiln atmosphere from the furnace and coolingzones to the glazing zone is minimized by the arrangement of the depending baflles J and a suit-- able regulation of the separate draft creating means for these sections to maintain ,balanced pressure conditions therein. I

On leaving the furnace zone thew-are enters an atmosphere of salt vapor circulating dgnvnwardly through the kiln chamber and in intimate contact with the inner and outer exposed surfaces of the ware. The salt fumes not absorbed by the ware are drawn downwardly thro'ughthe ware platform into the transverse truck channels B through the exhaust passages H,--and into the exhaust,

duct H by the draft connection thereto. Normally a reducing atmosphere is maintained in the glazing zone, butif desired, this atmosphere may be made neutral or oxinection with the air duct C The recirculation passage dampers areadjusted to regulate the amount of salt vapor returned tothe kiln chamber. It will be noted that the glazing zone is substantially independent in operas tion having a circulation system not affected by or affecting the circulation in the other portions of the kiln. "The heating action of the salting burners F serves to vaporize the glazing agent and to maintain theware at substantially the same temperature as leaving the furnace zone. On leaving the glazing zone, the war e is subjected to both indirect and direct cooling effects in the cooling zone, which gradually.

lower the temperature of the ware toa point atfwhich it can be safely removed from the kiln. As described heretofore ithe atmosphere control provisions in the cooling zone can be regulated to maintain any desired cool:

ing temperature curve therein, the regulation in effect being primarily "dependent on the character of thewarebeingtreatedL Itis advantageous in most glazing kilns to use a relatively long operating cycle and in. one such kiln incorporating my inventiomfor example, each ware truck requires 66 hours to pass through a complete cycle, of which pe,. riod about 18 hours are spent in the preheating zone, 17 in the furnace zone, 6 in the salts ing zone, and 25 in the cooling zone.

Amongthe advantages of the present tun-- nel kiln construction is the relatively large cross-sectional area of itskiln chamber which permits an increase" inthe ware tonnage carried during each cycle and an increase in.

length of the cycle Without a corresponding increase in kiln length. This increases the daily capacity of the kiln and reduces the;

number of trucks required in use andthe labor of handling the same. The various regulating provisions described permitan' accurate con-- trol oftemperature conditions through every.

zone of the kiln. The large numberof .rela

tively small fuelburners distributed in,.tl1e manner described over the elongated furnace zone andtheir capacity for indivi'dual regulation materially aids the maintenance of the most desirable temperatureconditions in that zone and eliminates thedevelopment ofiexcessive local temperatures therein. Themain heating of the Ware, Wlllch occurs in the fur nace zone, advantageously takesplacevbeneath the Ware with the "products of com}. bustion passing upwardly through the multi-, v plicity of channels in the trucks and formed by the ware. The surfaces of the ware, and partici'ilarly'the outer ware pieces, are not subportion of the kiln. The maintenance ofan; up-draft circulation of the'heating gases in:

the furnacevzone insures advantageousfheating conditions, and the use of anindependent down-"draft circulation of the salt fumes'in the glazingv zone in conjunction therewith increases'thekiln efiiciency. The ldi stribu i 'tion of the salt vapors throughout the space above the Ware" before coming into, contact withithe ware insures a uniform distribution of the glazing agent to all parts of the ware and consequently a uniform glaze. The

vides a ware supporting platform of substan I tial area andmaintains the ware in a stable. condition, and thetruck circulation channels are oflsu fiicientvolum e to provide asubstantially unrestricted gas flow .thereth rough. y

While the kiln is described and illustrated i v as being fired by fuel burners: using'premixed air and gas,f0t her types of heating means and 19;: a jected to any direct flame inpingement in any.

discharge position.

fuels can also be effectively used, such as clean producer gas, oil, or coal. Producer gas Would not require premixing with air. Fuel burners using oil would be supplied with an atomizing agent, such as air or steam.

The aspirating action described can be car ried out with either of these fuels. In some cases, 'coal'fired on grates in the side walls of the furnace and salting zones may be used effectively.

"In Figs..911, I have illustrated a modified form-of salting zone construction in atunnel kiln of this general type. In this arrangement, each salting burner F is positioned in the; lower end of a corresponding inclined passage R in the side wall of the kiln and opening to the kiln chamber A 7 above the upper level of the ware W'. The outer end of the salting burner passage is closed by a metal I plate R. Preheated air for combustion can be delivered to theburner, if desired, from the air duct 0* through a passage S controlled by a damper S. stored in a suitable external hopper GA open at its inner lower side GA to permit the's'alt therein to be scooped up and discharged through a corresponding salt inlet opening R in the kiln side wall. The bottom of the salt inletis inclined as shown and opens to the burner passage P; above-the Venturi block F The outer end of the salt opening is closedby a door T; pivotally connected to an oscillatable lever T, which is fixed on a.

shaft T This shaft carries an arm T on the outer end of which a conveying scoop or cut T is mounted. The door and scoop are simultaneously operated periodicallythrough a pivoted operating lever T connected to the lever T by a link T These parts are relatively arranged to permit the door to be raised before the scoop reaches its dotted line the scoop while passing into the open side of shown in Figs. 10 and 11, at the inner side of the burner passage R and below the coricothe hopperis delivered through the salt opening R as required. The salt comes to rest on a ledge P andsfiattened inverted V-shape, as

responding'inlet R The salt is vaporized during its passage to and while on the ledge P and delivered to the kiln chamber in a vaporized condition. Recirculation of the kiln atmosphereto' return the salt fumes not absorbed by the ware to the chamber is effected' through the exhaust passage H and a fume collecting flue Q, which opens to a longitudinal duct H" leading to a stack and also to the burner passage B through a passage Q adjacent the salt inlet openin The passages Q. can be controlled by dampers Q i in the manner heretofore described to regulate the fume recirculation; In some cases, the described manual feeding of the salt is preferred to the use ofinechanical arrangements. Due to the inc-lined arrangementof the The glazing salt is The salt taken up by" salting'burner passage R- in this construc-' tion, any molten salt or glaze 1n the passage ings. To avoid such a'condition Ihave pro:

vided discharge passage P in the side walls and opening at each side of the ledge P and which, prevent the accumulation 'of'molten material on the ledge and I thereby avoid any interruptions in the. kiln operation. (3011-; tinui'ty of operation is highly essential and seldom'attained heretofore. r

While in accordance withthe provisionsof the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the-art that changes may be made in the formof the apparatus disclosed Without departingfrom the spirit of my invention as setforth in the appended claims and that in some cases certain features of my in-' I claim as new and desire to secure by Letters Patent, is: v

1. The methodof glazing ceramic ware which comprises moving the ware through a kiln chamber, heating the ware during its passage through the chamber to a high temperature, introducing a glazing agent in finely divided form into a high temperature 3 section of the kiln chamber, vaporizing the glazing agent introduced by the COHlbl.lS-' tion of fuel burning in contaot'with said agent immediately adjacent the point' or with, and passing the glazing vapors and heating gases so formed downwardly through said kiln chamber in intimate contact with the exposed ware surfaces.

'2. The method of glazing ceramic ware which comprises moving the Ware through a kiln chamber; heating the ware during its passage through the. chamber to a high temperature, simultaneously introducing a com:

bustible gaseous mixture and a glazing agentin f nely dividedform into a high tempera- :ture section of the kilnchainber at the same point or points above the top of the ware therein, vaporiz iigjthe glazing agent introduced by burning said gaseous mixture and passing the glazing vapors and heating gases ioo points of introduction of the latter there-v section of the kilnchamber, vaporizing the 7 glazing agent introduced by the combustion of "fuel introduced therewith, passing the glazing vapors and heating gases so formed downwardly through said kiln chamber in intimate contact with the exposed ware sur-.

faces, withdrawing the glazing vapors .unabsorbed by the Ware from the kiln chamher, and recirculating a portion of thezizapors sowvithdrawn into contact with the a 4.1118 method; of glazing ceramicware which comprises moving the ware through a kiln chamber, heating the ware during its passage through the chamber to a high temperature, introducing a'combustible gaseous mixture and a glazing agent in finely divided form into a. high temperature section of the kiln chamber above the top of the ware therein, vaporizing the glazingagent introduced by burning said gaseous mixture,

passing the-glazing vapors and heating gases. so formed while distributed over a :major portion of said high temperature section downwardly through said kiln chamber and in intimate contact with the exposed'ware surfaces, withdrawing the glazing vapors unabsorbed by the-ware from the kiln chamher, and recirculating a portion of the va-' J pors so withdrawn into contact. with the ware. r v v i 5. The method of glazing ceramic ware which comprises moving the ware through a kiln chamber, heating the ware during its passage through the chamber to, a high temperature, and glazing the ware whileat' a high temperature by passingaglazing agent in vaporized 'form in a c'lo'sedflow circuit including the ware in said kiln chamber.

v6. The method of glazing ceramic ware which comprises movlng the ware through akiln' chamber, heating the ware duringits, passage through the chamberto a\l1igh;temperature, subjecting the ware while at a high temperature to the action of a vaporized glazing agentito form a glazeonvthe exposed ware surfaces, withdrawing theunabsorbed vapors from the kiln chamber, andreturn ing a portion of the vapors sowithdrawn into: contact with the ware. V p f 7. The method of glazing ceramic cware which comprises moving Ztheware through a" kiln chamber, heating the; warej during its passage through the chamber to'a high temperature, subjecting the ware while at a high temperature tojthe action of a-vaporized glazing-agent to form ;a glaze on the exposed waresurfaces, withdrawing'the unabsorbed vapors from the kiln chamber, and recirculating a predetermined portion of the vapor so withdrawn downwardlythrough said kiln' chamber;

8. The method of glazing ceramic Ware which comprises moving the ware through akiln chamber, heating the ware duringits;

passage to a high temperature by passing heating gases upwardly in contact with the Ware, and-subjectingthe Warewhile at said high temperature to the glaze, forming actionof a vaporized glazing agent passing downwardly through and in contact with the exposed-ware surfaces. i

9. Theimethod 1 or glazing .c-lainic m; which comprises moving the ware through a kilnchamber, heating the ware during its passagelto a high temperature by passing high temperature heating gases" upwardly through the ware andsubsequentlysubjecte ing the'ware while at said highgtemperature to the glaze forming action of a vaporized glazing agent passingdownwardly through" and in intimate contact with substantially all of the exposed goods surfaces.

10. Themethod ,of salt glazing ceramic v,

warewhich comprises moving the ware. through a kiln chamber, progressivelyheat ing the ware during its passage to a high temperature by the combustion of premixed air and gas below the ware and passing the products of vcombustion upwardlyv through and in intimate contact with theware,'sub jecting the ware while at a high tempera -v 'tureftothe action of salt vapors passed downwardly through and in intimate a contact with the goods, withdrawing theflunabsorbed salt vapors from the bottom of; the

kiln chamber, and returning the saltvaporsy so withdrawninto contact {with the'ware in the upper part of the kiln chamber 11. The'method of glazingceramic'ware which comprises moving tlie warethrough an elongated kiln chamber, heating the ,ware

during its passage" through the chamber to a high temperature, subjecting theware while at aY-high temperature to the action of a glazing agent vaporized .bythe burningof fluid v fuel and air in the kiln chamber, to form aglaze on" the exposed warexsurfaces, withdrawing the unabsorbed Vapors from the kiln chamber, recirculating'a portionof the vapors so withdrawninto contact withthe'ware and supplying preheated air for' combustion with a said recirculated vapors. H n 1 2. The method of ,glaz1ng. ceram1c,ware

which comprises moving] the ware through a kiln chamber, heating tlie wareduringits passage through the chamber to a high itemv perature, simultaneously introducinga combustible n iixture of air and gas andap'glazing (agent in finely dlvi'dedform into a high tem peratureisection of the kilnchamber at the:

same point or points above the; top of the intimate contact with the exposed ware sur;

faces, and regulating the character of the kiln atmosphere in the glazing zone by supplying preheated. air for combustion to the upper part of saidkiln chamber. 1 13. A continuous tunnel'kiln adapted for glazing ceramic ware and comprising means for moving the .ware throughan elongated kiln chamber, means for heating the ware during its passage through the chamber to a,

high temperature, means for simultaneously introducing a glazing-agent in hnely divided form anda combustible mixtureinto a high temperature section of the kiln chamber and burning said mixture therein to vaporize the glazii g agent introduced, and means for passingthe glazing vapors so formed down wardly through said kiln chamber and in intimate contact withtlie exposed ware surfaces.

14. A continuoustunnel kiln formed with airelongated ware passageway; extending through successive preheating, furnace, and

I glazing zones, means for passing heating to the ware in said kiln chamberincluding .an inclined passage in-one of the kiln side walls openingto the kiln chamber above the level of the ware therein, fuel burning means in the lower end of said passage, and means for mixing a glazing agent with the products of combustion from said fuel burning means.

16. A tunnel kiln car having asuperstructare adapted for supporting hollow ceramic ware having vertical passages therein, said superstructure comprising a longitudinal series of transverse refractory girders having enlarged base portions substantially in contact, recessed web portions cooperating to form transverse gas'channels opening at their upper ends into communication with said ware passages, and flat upper surfaces on said girders on WhlClfl' the ware 1s directly supported. I

' 117. A continuous tunnel kiln formed with an elongated kilnchamber extending through successive preheating, furnace, and 5 glazing zones, aseries of fluid fuel'burners located in the sidewalls of saidkiln'chamber at the bench level of the kiln in said furnace zone, a series of fluid fuel burners in the sidewalls of said kiln chamber above the normal; top" level of the ware in said glazing zone, means for discharging a finely divided glazing agent into said kiln chamber with the heating gases from said second burner-series,

means effecting. an upwardcirculation of heating in said furnace zone, means.j

' effecting a downward circulation of glazing vapors and heating gases in said glazingzone comprising a of exhaust passages'in' the kiln side walls ofsaid glazing zone, ELIldfIB circulation flues connectingjcerjtain of said exhaust with said second burner 18. A continuous tunnel kilnformed with an elongated kiln chamber extending through:

successive preheating, furnace .aiid'glazing zones, a series of fluid fuel'burners, located inthe side walls of said kiln chamber at. the

bench level of the kiln in said furnace zone, a series of fluid fuel burners in the s dewalls ofsaid kiln chamber above the normal top level of the ware in said glazing zones,"means for discharging a finely divided glazing,

agentinto said kiln chamber witlrthe' heating from said second burner-series,

,m-eai s} effecting an upward circulation. of heatinggases in said furnace zone, means effecting a downward circulation of'glazing' vapors and heating gases in said glazing zone comprising a series of exhaust passages in the kiln side walls of said glazing zone, .recircu lation flues connecting certain of said exhaust passages with said second burner. series, a preheated air conduit connected to said recirculation fines, and means for controlling the'amounts of air and gases passing into said recirculation flues from said air conduit and exhaust passages, respectively.

19. A continuous tunnel kiln formed with an elongated kiln chamber extending through successive preheating, furnace, and glazing zones, a series of fluid fuel burnerichambers in the side walls of said kiln chamber above,

the normal top level of the ware in said glazing zone, a fuel burner in each of said burner chambers, means for mixing a finely divided glazing. agent with the fuel supply to said burners, means effecting a downward circulation of glazing vaporsand heating gasesin said glazing zone comprising a series. of transverse exhaust passages in the kiln side walls ofsaidglazing zone, and vertical re circulation fiues connecting certain of-said exhaust passages witli'jsaid burner chambers, and means for controlling thepassage of gases through said. recirculat on flues;

20,.A continuous tunnel kiln formed an elongated kiln chamber extending through.

successive preheating, furnace, and glazing zones, a series of fluid'fuel burner chambers in the kiln sidewalls opening'to said kiln chamber above thenormal toplevel'of the ware in" said glazing zone,'a fuel burner in each OfSELlClburner chambers, manually operated means for discharging a finely divided glazing agent into said fuel burner chambers, means for preventingthe flow of liquetied glazing material through a p'r edeter mined portion of said burner chambers,

means effecting a downward circulation of glazing vapors and heating gases in said glazmg zone comprising a series of exhaust pasQ sages in the kiln side walls of said glazing zone, and recirculationflues connecting said exhaust passages with said burner chambers.

21. In glazlng ceramic ware in a con't1nuous tunnel kiln having a goods space which comprises a heating section including a high 1 temperature portion at one end of the section and a glazing section adjacent said ,portion, the method which consists in moving the goods treated first through the heating section and then through the glazing section of the goods space, passing heating gases at high temperatures upwardly through said' high temperature port-ion of said heating section in contact with the goods therein and thence longitudinally through the goods space in contact with the goods in a direction leading away from the glazing section, supplying a volatilized glazing agent to the up per portion of the glazing sectionymoving said agent downward through said glazing section in contact with the goods, and withdrawing said agent from the goods space at the bottom of the glazing section thereof.

22. In glazing ceramic ware in a continuous tunnel kiln having a goods space which comprises a heating section including ahigh temperature portion at one end of the section glazing section, moving the mixture of burning gases, gaseous productsand volatilizeol glazing agent formed by the combust on of i the fuel downward vthrough said glazingsection in contact with the goods, and withdrawsaid mixture from the goods space at the bottom of the glazing section thereof.

23. The combination in acontinuous time nel kiln for glazing ceramic ware having a goods spacecomprlslng heating and cooling sections and a glazing zone intermediate said sections and means for moving: goods successively through the heatingsection, the glazing section'and the cooling section, of means for introducingburning gases at high temperatures into the bottom'of the portion of g the said heating section adjacent the glazing section, and passingsaid gases upwardly.

in said section in contact with the goods therein and thence longitudinally through the portion of the goods space more remote from the glazin'g zone, means for supplying a glazing agent to the upper portion of saidfglaz ingzone,and means for withdrawing gases from the goodsspace at the bottom of the glazing zone portion thereof, wherebythel glazing agent is caused to pass downwardly in contact with the goods in said glazing'seo-i tion. 7 j I V c g '24. The combination in a continuous-Vtunnelkiln for glazing ceramic ware having a goods space comprising heating and cooling 7 sections and a'glazing zone intermediate said sections and means for moving goodssuccesslvely through the heating section, the glazing section and the cooling section,v means for introducing burning gases at high tem peratures into the bottom of the portion of" the said heating sectionadjacent the glazing section, and passing said gases upwardly in said'section in contact with the goods there- I in and thence longitudinally through the portion of the goods space more remote from the glazing zone, means for supplying a glazing agent, and fuel for. combustion in immediate contact with said agent to the upper 1 portion of said glazing zone, and means for withdrawing gases from the goods space at the bottomof the glazing zone portion thereof, whereby the glazing agentand products of combustion of said fuel are. caused to pass downwardly in contact with the goods insaid CONRAD DnEs s ER,"

glazing section. v 

